Transformer



April 3, 1934. l. H. SCLATER ETAL TRANSFORMER Filed Nov. 2 1933 LIQUID LEVEL Patentecl Apr. 3, 1934 UNITED STATES PATENT OFFICE TRANSFORMER Application November 2, 1933, Serial N0. 696,322

4 Claims.

Our invention relates to transformers and particularly to transformers having windings between which there is a considerable difference of potential while in operation. This condition is often present in a current transformer which may have one winding at the potential of a, high voltage circuit with which it is connected in series and another winding at very low potential and connected to some instrument such as a meter 01' relay. Considerable separation of the windings is necessary to provide space for the necessary insulation and such spacing 015 the windings is not conducive to good voltage ratio and phase angle accuracy. The general object of the invention is to provide an improved transformer with windings well insulated from each other but having good voltage ratio und phase angle accuracy.

The invention will be better understood from the following description taken in connection with the accompanying d rawing which is a sectional view of a transformer constructed in accordance with the invention.

The transformer shown in the drawing includes a winding 10 on a magnetic core 11 and a. winding 12 an a magnetic core 13. Bach of the cores 11 and 13 is of hollow cylindrical form but they are of difierent diameters, the core 11 having the smaller diameter anal with its winding 10 being arranged concentrically inside the core 13 and its winding 12.

The two cores 11 and 13 with their windings 10 and 12 are enclosed in a casing 14 which may contain an insulating liquid 15 in which the cores and windings are immersed. A center post 16 extends axially through the two cores 11 and 13 and connects the bottom of the casing 14 with its top or cover 17. The terminals of the winding 10 extend through bushings 18 in the top or cover 17 and the terminals 015 the winding 12 extend through bushings 19 in the side wall of the casing. The casing 14 is preferably grounded as shown at 20. Two insulating cylinders 21 and 22 insulate the winding 10 and its core 11 from the other winding 12 and its core 13 and from the center post 16.

Inasmuch as the windings 10 and 12 are an separate cores, it is necessary to provide a conductor which shall function as a common coupling winding surrounding both cores. This conductor as shown in the drawing includes ehe post 16 and the ca.sing 14 connectihg the ends of the post, both the post and the casing being Iormed, 01 course, of conductive material such as copper or brass. Thus, if the winding 10 is connected as the primary und. the winding 12 as the secondary oi the complete transformer, then the casing 14 with its center post: 16 functions as a secondary for the winding 10 and as a primary for the winding 12.

In its preferred application, the transformer will be used as a current transformer, the winding 10 being connected in series with a circuit which may be at a potential considerably above ground potential and the winding 12 being connected to an instrument such as a relay in some form of electric meter. The winding 10 is well spaced and insulated from the other parts which may be at much 1ower potential but the arrangement provided by the invention is very compact and it has been found that the voltage ratio and phase-angle accuracies are extremely good as compared with the corresponding accuracies 01 the usual well designed transformer.

The invention has been explined by describing and illustrating a preferred form thereof but it will be obvious that changes may be made without departing from the spirit of the invention and the scope of the appended claims.

What we claim a.s new and desire to secure by Letters Patent of the United States, is,

1. A transformer including two hollow cores, one of said cores being a.rranged inside the other a winding on each core, and a coupling conductor surrounding both cores.

2. A transformer including two hollow cylindrica1 cores, said cores being concentrically arranged with one core inside the other, a winding on ea.ch core, and a coupling conductor surrounding both cores.

3. A transformer including two hollow cores; a winding 011 ecah core, a conductive casing for said cores and windings, and a. conductor extendingthrough both cores with each end connected to said casing, whereby said conductor and casing foxm a coupling conductor for both cores.

4. A transformer including two hollow cylindrica1 cores, said cores being concentrically arranged With one core inside the other, a winding on each core, a conductive ca.sing for said cores and windings, a.nd aconductive post extending through both cores, said casing being connected to the opposite ends of said post to form a coupling conductor for both cores.

IVANHOE H. SCLATER. GUGLIELMO CAMILLI. 

